>>48396747It's a holdover from earlier in development when "Bird-Type" and "Flying-Type were seperate.
Flying/Normal types exist in Gen 1 because when the Dragon type was added at the final moment of development, memory/storage concerns meant that another type had to go, so the "Bird" Type and the "Flying" type were merged into the unified flying type we all know and love. The part-normal designation was to keep the birds in their own separate bird type even if the actually type was gone. It's also why in Gen 1 all Flying type moves are bird related like peck (because they were the old bird type moves) but all the wind moves like Gust were normal (the original no-birds-allowed flying type moves had to go somewhere).
